Sear mechanism



July 29, 1941., G. 50550 2,251,174

SEAR MECHANI SM Filed April 10, 1937 2 Sheets-Sheet 1 Fig.1 .9 -0 /776222078 7937/ W Fig. 3

INVENTOR= GIULTIO 60550 ATfoR N 5V6 J y 29, 1941. G. 50580 2,251,174

SEAR MECHANISM Filed April 10, 1937 2 Sheets-Sheet 2 Fig.2

Patented July 29, 1941 SEAR MECHANISM Giulio Sosso, Turin, Italy Application April 10, 1937, Serial No. 136,079 In Italy April 14, 1936 1 Claim.

This invention relates generally to sear mechanism comprising a trigger and pawl for automatic fire arms, more particularly automatic pistols, and it has for its object certain improvements relating to the sear and trigger mechanism, the most important of such improvements consisting in providing means to permit recock ing of the hammer by pulling the trigger.

The accompanying drawings show a construction of the object of this invention in connection with an automatic pistol of the recoiling barrel type.

Figures 1 and 2 show partly in section the weapon with the trigger and hammer in their released position, and partly drawn-back trigger and cooked hammer ready for firing.

Figure 3 shows the weapon directly after firing and before it takes the position shown in Figure 2.

Figure 4 shows diagrammatically the auto-- matic safety device.

Finally Figures 5, 6, 7 and 8 are enlarged fragmentary views of the trigger and hammer mech-= anism illustrating in greater detail the relative positions of the parts during various stages of operation.

Throughout the views the same reference numerals indicate the same or like parts.

The frame I of the weapon comprises the half 2, trigger guard and the chamber for the magazine, which in the example shown is of the curved endless belt type according to my copending application Ser. No. 82,695 filed on June 1, 1936. The breech bolt 3 is slidably fitted in the frame and extends to the further end of the barrel 4 contained in the breech bolt. The barrel is guided in front in the bush 5 mounted by a bayonet joint in the breech bolt and rests at its rear end on a larger cross pin 6 in the frame by means of the breech l of the barrel, engaging by means of two teeth after the manner of a rack with a set of teeth on the pin 6. A sleeve 8 is fitted on the barrel and is held against the breech l by means of the spring 9 stretched between the breech 'l and bush 5. The sleeve 8 is provided with two cross bolts 8a pressed in a direction opposite to the pressure of the spring 9 on the sleeve by a fork ii pivoted to the frame at Illa. The hammer H is pivoted to the back of the frame at Ila. The hammer is connected to the fork ID by means of the link I2, so that on oscillation of either of them in one direction, the other oscillates in the opposite direction.

A tooth l5 having an abutment I5a is articulated to the fork.

A pawl l4 rockably mounted on the trigger I3 pivoted to the frame at l3a cooperates with the abutment 15a of the rocking tooth I5 on the fork H]. A spring 16 seated in a recess in the trigger acts on the rear end of the pawl I4.

The pin t which is operatively connected with the barrel through the teeth on the breech l, is further operatively connected with the breech bolt 3 by means of an arm 11, shown in dotted lines in Figures 1 to 3, which is solidly fixed to the pin 6 and engages into a recess in the breech bolt. The barrel and breech bolt are thereby operatively connectedtogether, and as the barrel recoils by a small extent, by reason of the engagement of the sets of teeth it rocks the arm H which pushes the breech bolt backwardly compressing the spring 9 by the proper extent for introducing the fresh bullet into the barrel and cooking the hammer.

The extractor I8 is pivoted as usual to the breech bolt by its extensions [8a and retains the striker l9 which is provided with a damping spring 2%].

The weapon is provided with an automatic safety device maintaining the striker locked until the trigger is drawn back. This safety device consists of a cross member 22 (Figure 4) pushed by a spring 23 into the path of the striker for looking it. The cross member is formed at its end remote from the spring with an incline 22a along which the push rod l l may slide under the action of the trigger as the latter is depressed (Figures 2 and 3), moving the cross member against the action of the spring 23. The cross member has a notch 22!) which in the depressed position of the trigger comes underneath the striker permitting movement thereof. When the trigger is inoperative, the striker is locked and in its safety position, from which it is automatically released on depression of the trigger.

The weapon is loaded as usual by pulling the breech bolt which has a milled rear end. A spring controlled pawl 2| is provided in the frame and has a knob ZI'a and nose Zlb which is engaged by a mortise 3' in the breech bolt and holds the latter in its backward position for easy inspection of the weapon.

By pulling the breech bolt 3 backward, the hammer II is cooked and by rocking backward it oscillates the fork I0 forward by means of the link l2, said fork cooking the spring 9 by means of the sleeve 8. The hammer remains in the cocked position as the breech bolt turns forward to its normal position by the fact that the forward oscillation of the fork Ill has permitted the oscillating tooth l5 to become engaged with the stop I5b on the frame, as shown in Figure 2.

The weapon is ready for firing, but the striker is as yet locked by the cross member 22 because the spring I6 still pushes the trigger I3 forward.

On drawing back the trigger, at first the pawl I4 comes into contact with the abutment I'5a on the tooth I5, should this not yet have taken place, slightly compressing the spring I6, and the striker is released from the cross member (Figure 2). To fire the shot the trigger is drawn back a little further, now releasing the tooth I5 from the stop I51) and successively, the pawl I4 becomes disengaged from the tooth I5, for the rear portion of tooth I5 is raised during the rocking movement thereof by efiect of the pawl and, upon reaching a certain position, the pawl I4 slips above the abutment I 5a on the tooth I5. In this manner, the fork I is set free, so that the hammer connected to the fork by the link I2 may now freely be actuated by the spring 9.

When the shot has been fired, the barrel recoils by a few millimeters while the breech bolt thrown by the arm I! performs a long stroke (Figure 3) necessary for introducing the fresh bullet into the barrel and re-cocking the hammer, whereupon the arm takes again the position shown in Figure 2 as soon as the trigger I3 is released.

At this moment the spring I6 pushes the trigger I3 forward bringing the tip of the pawl l4 again opposite the abutment I5a on the tooth 5. The weapon is now ready for firing a new shot, unless the hammer is lowered by hand, in which case it is returned to the position of Figure 1 upon exerting a very slight pressure on the trigger I3 for releasing the tooth I5 from the abutment I 5b.

When after such releasing of the hammer by hand, the trigger I3 is pulled, the tip of pawl I4 abuts the shoulder or abutment I511 or pawl I5. On further movement of the trigger, the fork or sear member ID is oscillated and thus the hammer is re-cocked through the link l2. During these displacements the pawl I5 oscillates on its pivot on the fork I0 and after the hammer has been re-cocked the pawl tip, during the further movement of the trigger, is disengaged from the shoulder I5a. The fork is therefore free to oscillate backwards under the action of the spring 9, thus oscillating the hammer forward and firing the shot.

If we refer more particularly to Figure 5, the normal inoperative conditions and positions of the various parts of the sear mechanism are shown.

In other words, the main spring 9 is shown extended, the hammer II is on the breech bolt, the pawl l5 has passed over the abutment I51), the trigger has been returned outwards into the normal inoperative position pushed by the spring I5 and the end of the pawl I4 is in engagement with the notch i511 of pawl I5.

Assuming that the hammer II (Figure 6) is to be brought to the cocked position, this operation can be effected in two different ways. For example, if the firearm has not yet been loaded, that is to say if the cartridge has not yet been introduced into the barrel, the breech bolt is pulled back by hand. Through thismovement, the breech bolt, on striking the hammer, carries it into the cooked position and compresses, by means of the link, the main spring 9 and at the same time, by the anticlockwise oscillation of the fork sear member ID, the pawl I5 is brought behind the abutment I512 assisted in this movement by the spring I6. On the return movement the breech bolt introduces the cartridge into the barrel; during this movement the hammer is locked by engagement of pawl I5 on the abutment I5b.

On the other hand, if the firearm is already loaded, the trigger is pulled back by this movement, a counter-clockwise movement is imparted to the fork sear member through the pawl I 4 in engagement with the notch I5a and the pawl I5, so that cocking of hammer II and compression of the main spring 9 are started. As soon as the end of pawl I5 is disposed behind the abutment I51), its spring I6, through pawl I4, causes pawl I5 to oscillate in a clockwise direction, throwing it into engagement with the abutment I5b. If at this moment the trigger is released, the hammer remains in the cooked position.

If firing is intended to take place (Figure '7), the trigger I3 is pulled out further thus causing the fork sear member I!) to effect a counterclockwise rotation so as to bring the hammer into the full cocked position, and on further compressing the main spring 9 the pawl I5 is released from the abutment I5b.

By this further counter-clockwise rotation of the fork sear member I 0, the pawl I5, which has been rotated on the pin of the fork sear member Iii has reached such a position as to permit the end of the pawl I4 to slide (by effect of the pull on the trigger I3) on the inclined surface of the notch I'5b, releasing it from the latter (Figure 8).

As soon as this takes place, the fork sear member I0 which is no longer retained by the trigger, by a snapping movement produced by the extension of the main spring 9, effects a clockwise rotation causing the hammer II to snap on the striker I 9 for firing. During the firing movement the pawl I5, due to the sliding of the end of pawl I' l on the surface above its oscillation pin, cannot effect a clockwise rotation and therefore passes over the abutment and allows the hammer to perform its stroke. Upon, thereafter releasing the trigger I 3, the parts are returned into the position shown in Figure 4, that is to say the pawl I4 is returned by the spring I6 into the notch I5a.

The constructional details, type of weapon, method of loading, etc., may be largely varied from what has been described and shown by way of example without departing from the scope of this invention.

miat I claim is:

Sear mechanism for pistols, comprising a frame, a movable hammer on the frame capable of being cocked, a barrel, a main spring surrounding a barrel, a fork sear member journaled on the frame and coacting with said main spring, a link connecting the hammer to the fork sear member, so that when the hammer oscillates in the cooking direction, the fork sear member oscillates in the opposite direction to compress the main spring, a pawl journaled on the fork sear member and adapted to engage an abut- 1 ment on said frame when the hammer is brought into the cocking position and the main spring is compressed, a trigger, a second pawl journaled on said trigger, a second spring mounted on said trigger and acting on the second pawl to press its free end against the upper face of the first pa'w'l, the latter having an abutment oacting with said second pawl to bring the hammer into the cocked position and compress the main spring and also bring the first pawl into engagement with the abutment during the first part of the movement of the trigger, while the last part of the movement of the trigger produces first the disengagement of the first pawl from the abut-- ment and then the release of the second pawl from the abutment on the first pawl in order to release the main spring and operate the 5 hammer.

GIULIO SOSSO'; 

